One recent use of homodyne radar system involves the detection of minute body movements that are associated with human respiratory activity. This approach is based on the principle that breathing produces measurable phase changes in electromagnetic waves as they reflect off of the skin surface of the moving thorax of a living person. When the target surface is moving, as does the surface of the chest in conjunction with respiratory and cardiac activities, corresponding variations will be observed in the difference of the phase between the received and transmitted signal. The observed variations can be used to determine motion-related target parameters such as displacement and velocity.
Given the extreme sensitivity to slight motion that can be sensed with homodyne radar, a device has been developed called a “Radar Flashlight.” The Radar Flashlight is designed to allow police or the military to detect the respiration signature of a non-cooperative human subject behind a wall, door or an enclosed space with non-conductive walls. The device also has application to the location of conscious or unconscious persons in a smoke filled or chemical contaminated office building.
Currently, in operation, the Radar Flashlight is placed against the intervening wall or on a tripod and the homodyne radar system is activated by the operator. When the Radar Flashlight is not stabilized by the user pressing it against the wall or by placing it on a stabilizing tripod, the user's slight hand motion is detected by the Radar Flashlight as movement. Thus, when hand motion is present, the homodyne radar cannot effectively determine if the detected movement signature is from the subject or from the stationary wall.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.